Calcium phosphate bone cement/mesoporous bioactive glass composites for controlled growth factor delivery.

Calcium phosphate (CaP) bone cements are widely used for the treatment of bone defects and have been proposed to serve as a delivery platform for therapeutic drugs, proteins and growth factors into the defect region. However, they lack sufficient porosity to allow immediate bone ingrowth and thus foster rapid integration into the bone tissue. In this study we investigated a composite prepared from a hydroxyapatite forming bone cement and mesoporous bioactive glass (MBG) granules as a potential carrier for biologically active proteins. The mechanical properties of the composite were not compromised by up to 10 wt% MBG granule addition, which can be attributed to the strong interface between the cement matrix and MBG particles, however this modification induced a significant increase in porosity within 3 weeks ageing in an aqueous liquid. The release profiles of two proteins, lysozyme and the vascular endothelial growth factor (VEGF), could be controlled when they were loaded onto MBG granules that were subsequently embedded into the cement when compared to direct loading into the cement precursor. Both proteins were also demonstrated to maintain their biologic activity during embedding and release from the composite. These findings suggest the CaP bone cement/MBG composite developed in this study as a potential delivery platform for growth factors or other bioactive substances.

Bacterial concentration fluorescence immunoassay (BCFIA) for the detection of periodontopathogens in plaque.

A bacterial concentration fluorescence immunoassay (BCFIA) was developed to rapidly detect periodontopathic bacteria in human plaque samples. The BCFIA utilized fluorescent-tagged monoclonal antibodies (MAbs) directed against the lipopolysaccharide of selected Gram-negative bacteria. Microorganisms identified in plaque using the BCFIA included Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, and Fusobacterium nucleatum. The immunoassay procedure involved combining a patient's plaque sample with a species-specific fluorescein isothiocyanate-labeled MAb and then incubating the mixture in a specialized microtiter plate allowing the MAb to bind to its homologous bacteria. Bound and unbound fluorescent-tagged MAbs were separated by filtration and total bound bacterial fluorescence was determined with a fluorimeter. The relative number of a bacterial species in a given plaque sample was estimated by reference to a standard curve carried through the BCFIA. The BCFIA had a lower detection limit of near 10(4) specific bacterial cells in a mixed bacterial preparation or plaque sample. When compared to cultivable flora procedures in detecting the 4 periodontopathogens, the BCFIA had high levels of statistical sensitivity, 97% to 100%, while statistical specificity ranged between 57% and 92%. There was a 71% to 82% agreement between BCFIA and DNA probe methodology in detecting periodontopathogens in plaque. The BCFIA, when compared to cultivable flora, offers the advantage of evaluating both live and dead bacterial cells in plaque. This may in part, if not fully, explain the lower specificity values of the BCFIA when compared to cultivable flora. Screening plaque samples for periodontopathic bacteria is considerably faster and results in a greater frequency of detection with BCFIA than cultivable flora based methods.